This is in exact analogy to the sophists, who in their way of educating claim to educate young people in such a way that they will be able εὗ λέγειν, "to debate and speak well about everything." It is peculiar to both the sophists and the dialecticians κοινὸν δὲ πᾶσι τὸ ὄν ἐστιν (b20), "to have beings as a whole for their theme." περί μέν γὰρ τό αὐτό γένος στρέφεται ἡ σοφιστική καὶ ἡ διαλεκτική τῇ φιλοσοφία (b22f.). "Sophistry and dialectics move within the same field of beings as philosophy does," according to their claim. All three, namely the dialectician, the sophist, and the philosopher, claim to deal with the whole.
But this is the distinction: ἀλλὰ διαφέρει τῆς μὲν τῷ τρόπῳ τῆς δυνάμεως (b23f.), "philosophy distinguishes itself from the one, namely from dialectics, τῷ τρόπῳ τῆς δυνάμεως, by the type and the mode of competence." That is to say, there is a distinction regarding the extent to which each is adequate. Dialectics is not as adequate, it is not as adequate for its task as philosophy is. Dialectics is specifically, at b25, πειραστική, or in terms of Aristotle's paraphrase of this expression in the Topics, πεῖραν λαβεῖν,3 "it makes an attempt at something. " Dialectics makes an attempt-to do what? To exhibit beings in their Being. Dialectics is on its way to this goal, but it is not adequate. Dialectics is thus distinguished from philosophy proper with regard to the extent of the adequacy or proficiency. Dialectics remains preordained and subordinated to philosophy. τῆς δὲ τοῦ βίου τῇ προαιρέσει (b24), "from the other (i.e., from sophistry) philosophy distinguishes itself in the way of choosing in advance the mode of existence," to translate literally. That is, the βίος of the philosopher is devoted purely to substance [Sachlichkeit] rather than semblance. The philosopher, as the representative of this radical research, has absolutely and purely decided in favor of substance over semblance. In the sophist, too, there is a προαίρεσις, but a different one. His concern is education, and his determinate mode of existence comes down to enabling others εὗ λέγειν, "to debate well," about everything the philosopher deals with. What is completely disregarded is whether this ability to speak about things says anything substantial about them. In sophistry, as a study of its history also shows, the only concern is to be able to speak in a splendid way about anything whatsoever under discussion. Sophistry's ideal is a spiritual existence oriented solely toward the form of speech, which indeed meant much to the Greeks.
3. Sophistical Refutations I, 11, 171b3f.: τὸ φάναι ἢ ἀποφάναι ἀξιοῦν ... ἐστὶν ... πεῖραν λαμβάνοντος.